Cereal rust eradicant composition comprising a phenylhydrazone derivative and method of use



Unite 'CEREAL RUSTHERADICANT COMlOSITION COM- PRISING A PHENYLHYDRAZONEDERIVATIVE AND METHOD OF USE Van R. Gaertner and Dexter B. Sharp,Dayton, Ohio, asslgnors to Monsanto Chemical Company, St. Louis,

0., a corporation of Delaware No Drawing. Application September 21, 1954Serial No. 457,555

8 Claims. (Cl. 167-33) The present invention relates to new and usefulimprovements in biological toxicants and more particularly provides newand valuableeradicants for cereal plant rusts, especially wheat rust,and methods of treating plants susceptible to attack by rusts in whichmethods said eradicants are used. I i

We have found that unusually effective fungicidal compositions areobtained when the active ingredient is a hydrazone of a carbonylicdihydropyran selected from the class consisting of hydrazone's havingthe formula in which Z represents a divalent alkenyleneoxyalkylene chaincompleting the dihydropyran -n'ucleus and havinga total offrom to 11carbon atoms, R is a hydrocarbon radical free of acetylenie and olefinicunsaturation and containing from 1 to 12 carbon atoms and R is selectedfrom the class consisting of R and hydrogen; and a hydrazone having theformula in which R and R are as herein defined and Y is an alkyl radicalof from 1 to 12 carbon atoms.

The presently useful hydrazones are readily obtainable, in known manner,by the condensation of an appropriate dihydropyrancarboxaldehyde orcarboxylated dihydropyrone with an appropriate hydrocarbon hydrazine. i

HydraZine compounds employed for the preparation of the presently usefulcondensates have the formula statgs P 'c'lteflt r hydrocarbon radicalfree of non-benzenoid unsaturation attached to the same nitrogen atom,e. g., phenylhydra zine, p-tolylhydra zine, 2,4-dimethylphenylhydrazineor 2-ethylphenylhydrazine and the l-alkyl, aryl, aralkyl, alkaryl, orcycloalkyl derivatives thereof such as lmethyl-l-phenylhydrazine,l-isoamyl-l-phenylhydrazine, l-cyclohexyl-l-o-tolylhydrazine,l-benzyl-l-phenylhydrazine, 1,1-diphenylhydrazine, etc. In the usefulhydrazines,

there may be only one hydrocarbon radical attached to one of thenitrogen atoms or there may be two of the same hydrocarbon radicals ortwo dissimilar hydrocarbon radicals attached to the one nitrogen atom.Because of the easy availability of phenylhydrazine, the condensationproducts of this particular hydrazine derivative and the carbonylicdihydropyrans and dihydropyrones are advantageously used in thepreparation of the present fungicidalcompositions.

The dihydropyrancarboxaldehydes used in preparing the presently employedhydrazones have the formula in which Z represents a divalentalkenyleneoxyalkylene zones may be mentioned3,4-dihydro-2H-pyran-2-carboxaldehyde which is generally known asacrolein dimer; 5,6-dihydro-2,6-dimethyl-2H-pyran-3-carboxaldehyde, 3,4-dihydro-Z,5-dimethyl-2H-pyran-2-carboxaldehyde which is the dimer ofmethacylaldehyde; 3,4-dihydro-2-amyl- 2H-pyran-2-carboxaldehyde;5,6-dihydro-2H-pyran-3-carboxaldehyde; boxaldehyde; 3,4 dihydro 2Hpyran-3-carboxaldehyde, etc.

The carboxylated dihydropyrones used for preparing the rust-inhibitinghydrazones are the alkyl esters of 3,4-dihydro-2,2-dimethyl-4-oxo-2Hpyran. 6 carboxylic acid, e. g., methyl, ethyl, n-butyl, tert-amyl,Z-ethylhexyl, n-decyl or tert-dodecyl 3,4-dihydro-2,2-dimethyl-4eoxo-2H-pyran-6-carboxylates. They are obtained by reaction of mesityl oxidewith an appropriate alkyl oxalate. The butyl ester is commonly knownasindalone.

Cereal rust eradicants comprising the present hydrazones as theessential effective ingredients function as plant chemotherapeutantsagainst the various leaf and stem rusts of wheat, barley, 'rye, and oatsand other small grain crop plants. Such cereal rusts as the stern rustPuccinia graminis tritici, or the leaf rust P. rubigowem tritici or thestripe rust P. glumarum of wheat usually cannot be controlled by generalpurpose fungicides. The stem and crown rusts of oats (P. graminis avenueand P. coronata ave'nae), as Well as the stem rust of rye (P. graminissecalis) or the leaf rust (P. hordei) of barley display similarresistance. In prior art, much efiort has been expended in the past inbreeding rust-resistantstrains of these cereals; but as new strains of,e. g., wheat, are developed, new races of the above classes of rustsappear and proceed to attack the new, presumably rustresistant strainsof wheat. The history of breeding for rust-resistance thus comprises arecurrent introduction of cereal strains which are resistant toprevailing races of the rusts and subsequent appearance of new races ofrusts to which the recently introduced cereal strains are susceptible.Accordingly, the eradication of fungus growth by chemical treatment ofcereal plants has become subjected to close scrutiny. Unfortunately,most of the known fungicides have been found to be unsuitable atnon-phytdtoxic 3,45dihydro-3,4-dimethyl-2H-pyran-2-carent means ofapplication. Particularly when aerial dusting or spraying is thecontemplated 'means of application,

particle size and solubilityare of extreme importance.

Rust eradicant compositions may he prepared by mixing the presenthydrazones with dusting materials such as talc, clay, lime, bentonite,pumice, fullers earth, etc. The majority of the hydrazones will be foundto be water-insoluble. These may be dissolved in organic solventstherefor and the resulting solutions used as fungicidal orfungi-prevening sprays. small amount of a concentrated solution of thehydrazone compound in an organic solvent, e. g., cyclohexanone, may beadded to water in the presence of an emulsifying agent to form anemulsion, and the oil-inwater emulsion thus obtained is employed as aspray. Suspensions or dispersions of the hydrazone compounds in anon-solvent such as water, or aqueous solutions of the water-solublecompounds, are advantageously employed in the treatment of the plantfoliage.

I The present invention isfurther illustrated, but not limited, by thefollowing examples:

Example 1 The therapeutic effect of the phenylhydrazone of 3,4-dihydro-ZH-pyran-2-carboxaldehyde against wheat rust was determined asfollows:

Five uniform, six-day old seedlings of a rust-susceptible variety ofwheat (Seneca) were sprayed with water by means of an atomizer. Theindividual leaves were then gently rubbed between the thumb and indexfinger to remove the bloom, and then inoculated with Puc- Moreexpediently, a

iii

cinia rubigo-vera zritici by gently scraping, up and down the back sidesof the rubbed leaves, a scalpel which had been water-wetted and loadedwith spores of the organism. Following inoculation, the plants weresprayed with a fine mist of water and maintained for 48 hours in anincubation chamber at a temperature of 70 F. and a humidity of 100%.They were then transferred to greenhouse benches where they were keptfor another 48 hours. At the end of that time they were sprayed with anemulsion prepared as follows: a

The 3,4-dihydro-2H-pyran-2-carboxaldehyde phenylhydrazone (100 mg.) wasadded to 5 ml. of acetone, and there was then introduced to theresulting solution approximately 0.1 ml. of an emulsifying agent knownto the trade as Tween 20 and reputed to be a polyoxyethylene sorbitanmonolaurate. The whole was then diluted with 5 ml. of water to give anemulsion containing 1% by weight of the hydrazone. For the instant testthe 1% emulsion was further diluted with water to give a concentrationof 0.5% by weight of the test compound. Spraying of the plants with theemulsion was effected by means of an atomizer, 5 ml. of the emulsionbeing used per pot of 5 plants. The sprayed plants were then returned tothe greenhouse and held there for a Week. Observation of the plants atthe end of that time dis- 4 pyran selected from the class consisting ofhydrazones having the formula as /R R in which zrepresents thedihydropyran radicalformed by ring-closure of an alkenyleneoxyalkylenechain having a total of from 5 to 11 carbon atoms, R is a hydrocarbonradical free of acetylenic and olefinic unsaturation and containing from1 to 12 carbon atoms and R is selected from the class consisting of Rand hydrogen; and a hydrazone having the formula BIC-O (LCOOY in which Rand R are as herein defined and Y is an in which Z represents thedihydropyran radical formed by ring-closure of an alkenylene'oxyalkylenechain having a total of from 5 to 11 carbon atoms.

3. A wheat rust eradicant comprising water, an emulsifying agent, and aphenylhydrazone of an alkyl 3',4-'d ihydro 2,2 dimethyl 4 oxo 2H pyran 6carboxylate having from 1 to '12 carbon atoms in the alkyl radical.

4. A wheat rust eradicant comprising water, an emulsi fying agent, and aphenylhydrazone of a 3,4-dihydro-2H pyran-2-carboxaldehyde. .j'

5. A wheat rust eradicant comprising water, an emulsifying agent, and aphenylhydrazone of butyl 3,4-dihydro-2,2-dimethyl-4-oxo-2H-pyran-6-carboxylate.

6. The method of inhibiting the development of rust on wheat whichcomprises applying to the wheat a rust inhibiting quantity of ahydraz'one of a carbonylic dihydropyran selected from the classconsisting of hydrazones 3 having the formula in which Z represents thedihydropyran radical formed closed extensive suppression of rust in thecase of the inoculated and sprayed plants, and no evidence of anyphytotoxic effect of the spray. Similarly inoculated, but unsprayedplants, which had been maintained in the incubator and greenhouse forthe same length of time were found to be badly affected by the rust.

Example 2 sifying agent, and a hydrazone of a carbonylic dihydrobyring-closure of an alkenyleneoxyalkylene chain having a total of from 5to 11 carbon atoms, R is a hydrocarbon radical free of acetylenic andolefinic u'nsatura tion and containing from 1 to 12 carbon atoms and Ris selected from the class consisting of R and hydrogen; and a hydrazonehaving the formula in which R and R are as herein defined and Y is analkyl radical of from 1 to 12 carbon atoms.

7. The method of inhibiting the development of. rust onwheatwhichcomprises applying to thewheat a rust V inhibiting quantity of thephenylhydrazone of 3 ,4-dihy-' 1. A wheat rust eradicant comprisingwater, an emuldro-2H -pyran-2-carboxaldehyde. 8. The method ofinhibiting the development of rust on wheat: which comprises applying tothe wheat a rust inhibiting quantity of the phenylhydrazone of butyl3,4- dihydro-Z,2-dimethyl-4-oxo-2H-pyran-6-carboxylate.

References Cited in the file of this patent UNITED STATES PATENTSBonrath et a1. Sept. 15, 1936 6 FOREIGN PATENTS Australia July 6, 1939OTHER REFERENCES Horsfall: Fungicides and Their Action, vol. 2, 1945, p.132.

Frear: A Catalogue of lnsect. and Fung., vol. 1, p. 144, 1947, and vol.2, p. 43, 1948.

McNew: Phytopathology, vol. 39 (1949), pp. 721-751.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION February 241, 1959Patent -2 a75 124 Van R. Gaertner et a1.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction and that the saidLetters Patent should read as corrected below.

Column 2, line 33 for "methacylaldehyde" read methacrylaldehyde Signedand sealed this 11th day of April 1961,

(SEAL) fittest:

ERNEST w. $WIDER ARTHUR W. CROCKER A i Commissioner of Patents

1. A WHEAT RUST ERADICANT COMPRISING WATER, AN EMULSIFYING AGENT AND AHYDRAZONE OF A CARBONYLIC DIHYDROPYRAN SELECTED FROM THE CLASSCONSISTING OF HYDRAZONES HAVING THE FORMULA